This invention relates to a remotely located evaporator assembly including a heating system for a truck climate control system and specifically to construction of a plastic outer covering compatible with the heating system of the evaporator assembly.
Delivery trucks and trailers transporting temperature sensitive cargo include specially designed climate control systems. As one example, a truck refrigeration system includes a motor and a compressor mounted outside of a cargo area. Refrigerant flows from the compressor into the cargo area to at least one remotely located evaporator unit. The refrigerant flows through an evaporator coil in the evaporator and back to the compressor. Cooling fans mounted within the evaporator blow air across the evaporator coils such that the air is cooled and expelled into the cargo area to maintain a desired temperature.
One type of evaporator includes a heating system for heating of the compartment and for defrost of the evaporator coils. Typical heating systems utilize a hot gas or fluid that is flowed into a separate coil adjacent the evaporator coil. Another type of heating system includes electric heating strips positioned below the evaporator coil.
Evaporators mounted within the cargo area are typically composed of a support housing mounted to an interior surface of the cargo area. The evaporator coils and the cooling fans are mounted to the support housing. An outer skin conceals and protects the cooling fans and the evaporator coils. Typically, the outer skin is formed from aluminum. One type of evaporator disclosed in co-pending patent application titled xe2x80x9cEVAPORATOR WITH PLASTIC OUTER COVERINGxe2x80x9d, Ser. No. 10/003,549, filed Oct. 24, 2001, and assigned to the applicant of this invention includes a plastic outer covering. The plastic outer covering provides design advantages by reducing overall evaporator weight and by simplifying manufacture and assembly. However, the plastic outer cover is not compatible with evaporators having heating system because the plastic material is susceptible to damage from exposure to the heating system.
For this reason, it is desirable to develop an evaporator assembly including a heating system that can realize the benefits of incorporating a plastic outer covering.
An embodiment of this invention is an evaporator assembly having a heating system and a plastic outer covering protected from damage from radiant heat by a heat shield positioned between the heating system and the plastic outer covering.
The evaporator assembly includes a support housing for mounting to an internal compartment of a delivery truck or trailer. At least one evaporator coil mounts to the support housing along with at least one cooling fan. A heating system is provided, such as a plurality of electric heating strips positioned below the evaporator. A plastic outer covering encloses and protects the evaporator coil and cooling fans. A drain pan integrally formed within the plastic outer skin collects condensation and moisture dripping from the evaporator coils. A heat shield attached between the drain pan and the heating strips attenuates radiant heat that may otherwise damage the plastic outer covering.
The heat shield includes a plurality of openings to allow moisture to flow through to the drain pan. An embodiment of the heat shield covers the entire drain pan section of the plastic outer covering. Water and moisture within the drain pan may be sprayed from the interior of the evaporator assembly by the blowing cooling fans causing undesirable dripping of water from the evaporator into the cargo and storage area. The heat shield covering the entire drain pan buffets airflow across water within the drain pan to prevent spraying.
The heat shield attenuates the radiation of heat onto a plastic outer covering to prevent damage and allow the use of a plastic outer covering in evaporator assemblies including heating systems to realize of cost and weight benefits associated with the use of plastic outer coverings.